1. Field of the Invention
This invention relates to fuel pressure regulators for use in fuel delivery systems of vehicles, and more particularly to diaphragmed fuel pressure regulators.
2. Description of the Related Art
Fuel pressure regulators for use in fuel delivery systems of vehicles are well known in the art. In a typical fuel delivery system for a vehicle, the fuel delivery system includes a fuel tank, a fuel pump, a fuel filter, a fuel pressure regulator, a fuel return line, and a fuel metering device for supplying the appropriate amount of fuel to the vehicle engine.
The fuel pump, typically electrically operated, constantly draws fuel through an inlet disposed within the fuel tank. The fuel is forced through the pump outlet where it enters a fuel filter/regulator assembly through a fuel supply port. Most of the fuel passes through the fuel filter and out through an outlet port that is connected to a fuel line that leads to a fuel metering device, such as a carburetor or fuel injectors, for supplying fuel to the vehicle engine. Due to the fuel pump constantly pumping fuel into the fuel line at flow rates usually higher than what is required by the engine, a device is required to return excess flow back to the tank to avoid excess pressure buildup. Most modern fuel delivery systems require that the pressure in the fuel metering device remain relatively constant, within certain tolerances. As such, a fuel pressure regulator is required to regulate the pressure in the fuel line. The fuel pressure regulator acts as a pressure release valve by enabling the excess fuel to be returned to the fuel tank, thus relieving the excess pressure in the fuel line. The fuel pressure regulator acts by opening a valve member when the pressure on the upstream side of the regulator exceeds a predetermined pressure level. When the pressure on the upstream side of the regulator returns to the predetermined pressure level, the valve member closes. Thus the fuel pressure regulator acts to keep the pressure in the fuel line relatively constant within certain prescribed tolerances.
Most fuel pressure regulators utilize a diaphragm and valve assembly which act to seal the upstream side of the regulator from the downstream side of the regulator. When the pressure on the upstream side of the diaphragm exceeds a predetermined pressure differential, the diaphragm is caused to deflect thus causing a valve member to open to release fuel through the regulator and out through the return line where it is returned to the fuel tank. Thus, it should be appreciated that if the diaphragm does not properly seal the upstream side of the diaphragm from the downstream side of the diaphragm, it would be impossible to regulate the fuel line pressure because a proper pressure differential could not be maintained. It should be readily apparent, then, that the life of the fuel pressure regulator is dependent on the life of the diaphragm. If the diaphragm fails to properly seal or becomes worn, the performance of the pressure regulator will suffer or fail.
In most conventional pressure regulators the diaphragm is typically fabricated from synthetic rubber and is usually restrained within the housing by crimping or clamping it between the upper housing portions and lower housing portions of the regulator. The clamping pressure is critical. Too little pressure on the edges of the diaphragm and the diaphragm will not be adequately sealed or held in place. Too much clamping pressure causes premature failure of the diaphragm where it is clamped. Since there is such a narrow tolerance for the clamping pressure, this increases the costs of manufacture and the likelihood of failure if tolerances are not met Consequently, there is a need for a solution to this problem.
Thus, there is a need in the industry for an extended life pressure regulator which secures the diaphragm in the device without direct clamping forces yet maintains an adequate seal between the upstream and downstream sides of the diaphragm.
Additionally, there is a need in the industry for improving the seating characteristics of the valve member for creating a tighter seal between the upstream side of the diaphragm and downstream side of the diaphragm. By improving the seating of the valve member, stricter tolerances can be achieved and thus the efficiency of the fuel delivery system can be improved.
Furthermore there is a need in the industry for miniaturizing fuel pressure regulators and for reducing the costs of manufacturing fuel pressure regulators.